firmware: ti_sci: Mark driver as non removable

The TI-SCI message protocol provides a way to communicate between
various compute processors with a central system controller entity. It
provides the fundamental device management capability and clock control
in the SOCs that it's used in.

The remove function failed to do all the necessary cleanup if
there are registered users. Some things are freed however which
likely results in an oops later on.

Ensure that the driver isn't unbound by suppressing its bind and unbind
sysfs attributes. As the driver is built-in there is no way to remove
device once bound.

We can also remove the ti_sci_remove call along with the
ti_sci_debugfs_destroy as there are no callers for it any longer.

Fixes: aa276781 ("firmware: Add basic support for TI System Control Interface (TI-SCI) protocol")
Reported-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Closes: https://lore.kernel.org/linux-arm-kernel/20230216083908.mvmydic5lpi3ogo7@pengutronix.de/Suggested-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Dhruva Gole <d-gole@ti.com>
Link: https://lore.kernel.org/r/20230921091025.133130-1-d-gole@ti.comSigned-off-by: Nishanth Menon <nm@ti.com>

drivers/firmware/ti_sci.c

@@ -190,19 +190,6 @@ static int ti_sci_debugfs_create(struct platform_device *pdev,
 	return 0;
 }
 
-/**
- * ti_sci_debugfs_destroy() - clean up log debug file
- * @pdev:	platform device pointer
- * @info:	Pointer to SCI entity information
- */
-static void ti_sci_debugfs_destroy(struct platform_device *pdev,
-				   struct ti_sci_info *info)
-{
-	if (IS_ERR(info->debug_region))
-		return;
-
-	debugfs_remove(info->d);
-}
 #else /* CONFIG_DEBUG_FS */
 static inline int ti_sci_debugfs_create(struct platform_device *dev,
 					struct ti_sci_info *info)
@@ -3445,43 +3432,12 @@ static int ti_sci_probe(struct platform_device *pdev)
 	return ret;
 }
 
-static int ti_sci_remove(struct platform_device *pdev)
-{
-	struct ti_sci_info *info;
-	struct device *dev = &pdev->dev;
-	int ret = 0;
-
-	of_platform_depopulate(dev);
-
-	info = platform_get_drvdata(pdev);
-
-	if (info->nb.notifier_call)
-		unregister_restart_handler(&info->nb);
-
-	mutex_lock(&ti_sci_list_mutex);
-	if (info->users)
-		ret = -EBUSY;
-	else
-		list_del(&info->node);
-	mutex_unlock(&ti_sci_list_mutex);
-
-	if (!ret) {
-		ti_sci_debugfs_destroy(pdev, info);
-
-		/* Safe to free channels since no more users */
-		mbox_free_channel(info->chan_tx);
-		mbox_free_channel(info->chan_rx);
-	}
-
-	return ret;
-}
-
 static struct platform_driver ti_sci_driver = {
 	.probe = ti_sci_probe,
-	.remove = ti_sci_remove,
 	.driver = {
 		   .name = "ti-sci",
 		   .of_match_table = of_match_ptr(ti_sci_of_match),
+		   .suppress_bind_attrs = true,
 	},
 };
 module_platform_driver(ti_sci_driver);